This application claims the benefit of Korean Application No. 2000-7152 filed on Feb. 15, 2000, which is hereby incorporated by reference.
1. Field of the Invention
This invention relates to a liquid crystal display, and more particularly to a multi-domain liquid crystal display. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for a liquid crystal display that has a wide viewing angle and a simple structure.
2. Description of the Related Art
An active matrix liquid crystal display (LCD) requires a thin film transistor (TFT) as a switching device to display moving pictures. Since an LCD can be fabricated as a smaller dimension than a CRT, it has been extensively used in various applications such as a personal computer, a notebook computer, a copy machine, and a portable equipment, etc.
A twisted-nematic (TN) liquid crystal having a twist angle of 90xc2x0 is mainly used as a liquid crystal for the LCD. However, the TN-LCD has a limited viewing angle. In order to improve such a deficiency, a two-domain TN-LCD has been suggested.
As shown in FIG. 1, a pixel of the two-domain TN-LCD includes two sub-domains having two different rubbing directions. A C-plate 2, a first alignment film 3, an O-plate 4, a common electrode layer 3 formed of indium tin oxide (ITO), and a second alignment film 6 are disposed between a front transparent substrate 1 and a liquid crystal 7. Similarly, a C-plate 12, a first alignment film 11, an O-plate 10, a pixel electrode 9 formed of ITO, and a second alignment film 8 are disposed between a rear transparent substrate 13 and the liquid crystal 7. The C-plates 2 and 12 have optical axes parallel to the Z-axis direction, so that they are vertical to the liquid crystal display panel. The O-plates 4 and 10 are patterned to have different tilt angles for each domain. The first alignment films 3 and 11 between the C-plates 2 and 12 and the O-plates 4 and 10 serve as an adhesive for attaching the C-plates 2 and 12 to the O-plates 4 and 10, respectively. They are then rubbed to have different alignment directions for each domain, thereby determining alignment directions of the O-plates 4 and 10. The second alignment films 6 and 8 have a liquid crystal align in different directions for each domain.
As shown in FIG. 2, polarizers 14 and 15 having polarization directions perpendicular to each other are formed on the front and rear transparent substrates 1 and 13 for a two-domain TN-LCD. Light incident and outgoing sides of the liquid crystal cell 20 are parallel to the transmission axis.
The conventional two-domain TN-LCD can improve a viewing angle by rotating a liquid crystal within a pixel to the opposite direction for each domain. The two-domain TN-LCD shown in FIG. 1 requires the C-plates 2 and 12 and the O-plates 4 and 10 on both the upper substrate and the lower substrate in order to improve a viewing angle. Thus, since the conventional two-domain TN-LCD employs a 90xc2x0 TN, multi-layer optical films should be used for an optical compensation for each domain. Also, in the two-domain TN-LCD in FIG. 1, the first alignment films 3 and 11 arranged between the C-plates 2 and 12 and the O-plates 4 and 10 should be rubbed twice or have different alignment directions for each domain by a photo-alignment method. Furthermore, since a liquid crystal having a 90xc2x0-TN mode is used, the second alignment film 6 contacting the liquid crystal 7 should be aligned by twice rubbings to differentiate an alignment direction for each domain. As a result, the conventional two-domain LCD has problems in that the number of process increases and the process becomes complicated in an overall fabricating process.
Accordingly, the present invention is directed to a multi-domain liquid crystal display and method of fabricating the same that substantially obviates one or more of problems due to limitations and disadvantages of the related art.
An object of the invention is to provide a liquid crystal display that has a wide viewing angle and a simple structure.
Additional features and advantages of the invention will be set forth in the description, which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a liquid crystal display includes first and second substrates, a liquid crystal layer between the first and second substrates, wherein the liquid crystal layer a twist angle of at least 90 degrees, and an optical plate between the liquid crystal layer and the second substrate, wherein the optical plate has an optical axis horizontal to the first and second substrates.
In another aspect of the present invention, a method of fabricating a liquid crystal display having first and second substrates includes the steps of forming a liquid crystal layer between the first and second substrates, wherein the liquid crystal layer has a twist angle of at least 90 degrees, and forming an optical plate between the liquid crystal layer and the second substrate, wherein the optical plate has an optical axis horizontal to the first and second substrates.